Effects of bath annealing parameters on the microstructures and mechanical properties of thin specification cold-rolled IF steel

摘要

The effects of annealing parameters on cold-rolled IF steel was finished via modeling experiments.Cold-rolled steel sheet with first reduction rate of 50％ and 2rd reduction of 80％ was chosen in the laboratory,after the soaking stage the steel sheet was cooled down to 550℃ and air cold to room temperature.Modeling experiments were aimed at studying the recrystallization rule of thin specification cold-rolled IF steel and confirming the effects of main annealing process parameters (annealing temperature,soaking time) on the deep-drawing performance.The results of the study show that,the recrystallization temperature of thin specification IF steel is 20℃ lower than that of conventional thickness of specifications,the scope for 540 ℃ ～640 ℃,and complete recrystallization happens when it is above 640 ℃.The annealing temperature has significant effects on the deep-drawing performance.When below 700 ℃, the higher the heating temperature,the higher the elongation and r value.But higher temperature (such as 720 ℃) would lead to coarse grains and decrease in the ductility.Grain size and r value increase gradually with the growth of soaking time.{111} texture forms in annealing process,and {111} oriented grains grow at the expense of other oriented（mainly {100} oriented）grains during grain growth after recrystallization.Higher distortion energy stored in cold-rolled process makes thin specification IF steel with a high ratio of {111} 〈110〉/{001} 〈110〉.